Recent measurements indicate that the emission of some secondary electrons depends on interaction between the primary electron and ihe solid plasma as a whole. the co-operative interaction as opposed to the individual interaction of current theories. ln explaining secondnry emission, it is suggested that the injection of a primary across the boundary will result in transient motions of the negative charge cloud such that a high local negative charge density forms about the point of entry after a time of the order of the period of the plasma oscillation. The rise of this density forces electrons successively over the work-function barrier and accelerates them only slightly after ejection. Such secondaries will be instantaneous to a degree beyond experimental requirements. nearly independent of the detailed properties of the primary, of low emission velocity since acceleration after emission is due at most to few electron charges. Emission energies will cover a coniinuous range since acceleration will depend on the rate of build-up of surface charge after ejection, that is. on the phase of the plasma cycle at efection. At low primary velocities little energy will be transferred to the plasma since the charge cloud can adjust itself to equilibrium with the movingmore » charge at all stages. Maximum energy will be transferred when the primary electron travels one interaction distance within the plasma in a time of the order of the plasma cycle. Above this velocity energy transfer will fall slowly. (J.H.M.)« less